Please enable JavaScript.
Coggle requires JavaScript to display documents.
Object-Oriented Data Bases - Coggle Diagram
Object-Oriented Data Bases
Motivation for Object Database Management
need to store large amounts of complex data and integrate complex data with simple data
The ability to jointly use standard and complex data
An object-oriented approach is preferable for:
CAD
Multimedia systems and CASE tools
Geographic information systems
Document storage and retrieval systems
Object-oriented software system concepts
object type - data and operations
object
operation - a set of actions
method - the way an operation is to be performed
encapsulation - hide internal structure of class
inheritance
polymorphism - a different object form
messages - events
Architectures for ODM
Large Objects and External Software
Complex data are stored as a binary or text large object
BLOB and CLOB
Software external to the DBMS displays and manipulates large objects
Advantages
is simple to implement and is universal
All kinds of complex data can be stored
Large market for third-party software
Disadvantages
No optimization is possible
Data cannot be filtered using characteristics of large objects
No indexes can be used to select records
Additional disk accesses may be necessary.
order of the large objects may not coincide
Specialized Media Servers
Complex data reside outside of a DBMS
Manipulate a single kind of complex data
Using an application programming interface (API) to access complex data
The API`s set of procedures
retrieve
update
transform
Advantages
Better performance than the large object approach
Provide good performance for specific kinds of complex data
Disadvantages
Not enough flexibility
The range of operations may be limited
When combining simple and complex data perform is poorly
optimizer cannot jointly optimize simple and complex data
Transaction processing is limited to simple data
Object Database Middleware
Circumvents problems with media servers by simulating object features
clients send SQL statements to middleware, which makes API calls to media servers and sends SQL statements to database servers
The SQL statements can combine operations on simple and complex data
relieves the user of knowing a separate API
integrate complex data with relational databases
Disadvantages
some of the complex data could not be combined easily with simple data
can suffer performance problems because of a lack of integration with a DBMS
Combining complex and simple data suffers the same performance problems
cannot optimize requests that simultaneously combine simple and complex data
can provide transaction
ORDMS for User-Defined Types
user-defined types to provide additional query capabilities
Almost any kind of complex data can be added as a user-defined type
User-defined types involve a table-driven architecture
Architecture
The object query processor uses table-driven code
The parser decomposes references to expressions
The display manager controls the presentation of simple and complex data
The optimizer searches for storage structures that can be used to optimize
The relational kernel comprises transaction processing, storage management, and buffer management
Disadvantages
reliability may be a concern
user-defined types can be difficult to implement
implementation errors can affect the integrity
third-party data types can be subject to viruses
Object-Oriented Database Management Systems
proposed an object definition language (ODL) and an object query language (OQL)
preceded object-relational technology offerings by 10 years.
The ODMG group disbanded in 2001 and development of ODMG-compliant DBMSs has faltered also
unable to find a significant commercial niche